The present invention is concerned with novel pyrimidopyrimidine derivatives, pharmaceutically acceptable salts thereof, a process for producing then and pharmaceutical compositions containing then as an active ingredient.
It is known that the so-called "chemical mediator", i.e. histamine, serotonin or SRS-A, plays an important role in the appearance of various allergic symptoms in the human body. Thus, since the drug which antagonizes such biochemical substances and/or inhibits their release would be useful for treating or preventing allergic diseases, some compounds have been synthesized and tested in the field so far.
As a result of investigations upon a drug acting on allergic diseases, the inventors have found that the pyrimidopyrimidine derivative of the present invention has an excellent anti-allergic effect.
An object of the present invention is to provide novel pyrimidopyrimidine derivatives and pharmaceutically acceptable salts thereof which are useful for treating or preventing allergic diseases as well as low toxicity and less side effects.
Another object of the invention is to provide a process for producing pyrimidopyrimidine derivatives or pharmaceutically acceptable salts thereof.
A further object of the invention is to provide a pharmaceutical composition containing at least one of the pyrimidopyrimidine derivatives or pharmaceutically acceptable salts thereof as an active ingredient.